Ch 1 structure, and function of the muscular nervous and skeletal system

Major Functions of Muscle

Produce movement, maintain posture, stabilize joints, generate heat, move substances through the body, and produce force against external resistance.

Skeletal Muscle

Striated and voluntary muscle type attached to bones.

Cardiac Muscle

Striated muscle type that is involuntary and found in the heart.

Smooth Muscle

Non-striated and involuntary muscle type located in internal organs and blood vessels.

Epimysium

The connective tissue that surrounds the entire muscle.

Perimysium

The connective tissue that surrounds a fascicle, a bundle of muscle fibers.

Endomysium

The connective tissue that surrounds individual muscle fibers (cells).

Myofibril

Long structures inside the muscle fiber responsible for contraction.

Sarcomere

The basic functional/contractile unit of skeletal muscle, extending from one Z-disc to the next.

Actin

The thin filament in muscle fibers responsible for contraction.

Myosin

The thick filament containing myosin heads that interact with actin.

Z-disc

Defines the boundaries of the sarcomere.

Calcium in Muscle Contraction

Calcium binds to troponin, initiating muscle contraction by moving tropomyosin away from the actin-binding sites.

Sliding-Filament Theory

Explains how skeletal muscle produces force through the sliding of actin past myosin, resulting in sarcomere shortening.

Motor Unit

Consists of one motor neuron and all of the muscle fibers it innervates.

Afferent Nerves

Sensory nerves that carry information from the body to the CNS.

Efferent Nerves

Motor nerves that carry information from the CNS to muscles and glands.

Somatic Nervous System

Controls conscious movements of skeletal muscles and processes sensory information.

Autonomic Nervous System

Regulates involuntary functions such as heart rate and digestion.

Osteoblasts

Cells responsible for building and forming new bone.

Osteoclasts

Cells responsible for breaking down and resorbing bone.

Tendons

Connect muscles to bones, transferring muscular force to facilitate movement.

Ligaments

Connect bones to other bones, stabilizing joints and controlling movement.

Muscle Spindle

A sensory receptor that detects changes in muscle length and contributes to the stretch reflex.

Golgi Tendon Organ (GTO)

A sensory receptor that detects changes in muscle tension and regulates muscle force.

Types of Muscle Action: Concentric

Muscle action where the muscle produces force while shortening.

Types of Muscle Action: Eccentric

Muscle action where the muscle produces force while lengthening under tension.

Types of Muscle Action: Isometric

Muscle action where the muscle produces force without appreciable change in muscle length.

Type I Muscle Fibers

Slow-twitch fibers that are fatigue resistant and suited for endurance activities.

Type IIa Muscle Fibers

Fast oxidative-glycolytic fibers, both fast and moderately fatigue resistant.

Type IIx Muscle Fibers

Fast glycolytic fibers, very fast but less fatigue resistant, suited for short, intense efforts.

Central Nervous System (CNS)

Comprises the brain and spinal cord.

Peripheral Nervous System (PNS)

Comprises the nerves outside the brain and spinal cord.

Neuromuscular Junction (NMJ)

The communication point between a motor neuron and a skeletal muscle fiber.

Acetylcholine (ACh)

The primary neurotransmitter at the neuromuscular junction.

Proprioception

Information about body position and movement, including muscle length and tension.

Bone Remodeling

The process by which bone tissue is continually renewed, involving osteoblasts and osteoclasts.

Axial Skeleton

The central axis of the body, including the skull, vertebral column, and ribs.

Appendicular Skeleton

Includes the limbs and their attachments.

Types of Bone: Long Bones

Examples include the femur and humerus.

Types of Bone: Short Bones

Examples include carpals and tarsals.

Types of Bone: Flat Bones

Examples include the sternum and scapula.

Types of Bone: Irregular Bones

Examples include vertebrae and some facial bones.

Resistance Training

Exercise that places mechanical stress on bone to improve bone health.

Joint Classifications

Fibrous, cartilaginous, and synovial joints, with synovial joints allowing substantial movement.

Connective Tissue: Tendon vs. Ligament

Tendon connects muscle to bone; ligament connects bone to bone.

Proprioception Receptors

Muscle spindle detects length/stretch; GTO detects tension/force.